As the development of nanoscale semiconductor devices and systems increase, new processes and materials are needed to fabricate such semiconductor devices and components. While feature sizes on the semiconductor devices are decreasing, the cost of lithographic tools is increasing exponentially. Further reductions in feature size are often restricted by the lower limit of dimensions that can be achieved using lithographic methods. Semiconductor devices having features of about 60 nanometers (nm) or less, which are referred to herein as “sub-lithographic” features, are difficult to produce using conventional lithography.
Microcontact printing is one method for creating sub-lithographic features on semiconductor devices. The technique creates self-assembled monolayers (SAMs) on specific sites on a surface of a substrate of the semiconductor device. In a conventional process, a master mold with topographical features is prepared by photolithography or electron (e-beam) lithography. Referring to FIG. 1A, a stamp substrate 10 having a resist 12 thereon creates a pattern on a surface of the stamp substrate 10. An elastomer casing 14, conventionally formed from polydimethylsiloxane, is deposited over the stamp substrate 10 and resist 12 and cured. The stamp substrate 10 and resist 12 are separated from the cured elastomer casing 14 to form a soft stamp 14′ with topographical features. (FIGS. 1B and 1C) The soft stamp 14′ includes a pattern that corresponds to the pattern in the resist 12, which pattern is to be formed on the semiconductor device. The soft stamp 14′ is then wetted with an ink 16 and brought into contact with a receptor substrate 18. (FIG. 1D) The ink is physisorbed on the soft stamp 14′ and is transferred to the receptor substrate 18 to form SAMs 20. (FIG. 1F) Theoretically, the SAMs 20 are formed only in regions where the ink 16 contacts the receptor substrate 18. However, the physisorbed nature of the ink 16 leads to poor resolution of the stamped features on the receptor substrate 18 as ink 16 not in contact with the receptor substrate 18 wicks down the soft stamp 14′ due to capillary action. Another disadvantage is that the stamped features are no smaller than the lithographically defined features of the soft stamp 14′.
Attempts have been made to prepare sub-lithographic features on semiconductor devices by other methods known in the art. For example, e-beam lithography and extreme ultraviolet (EUV) lithography have been used in attempts to prepare such sub-lithographic features. However, widespread use of such methods has been hampered by difficulties including, for example, high costs and/or incompatibility with high throughput production methods. Accordingly, improved methods and systems for preparing sub-lithographic features on semiconductor devices are desired, as are stamps for achieving same.